i had one of those days yesterday as well. think it's because his schedule was out of wack, and he was bored and tired.
i just grinned and dealt. they're puppies, gonna have those days. i did put him for a time out when he got too mouthy or the barking started. it took some time, but he calmed down.
just remember, stay calm.
lol.. what an adorable pic of him. he looks so innocent.. haha